1. Field of the Invention
This invention relates to a process is for paraffin-olefin alkylation producing highly branched paraffins under strong acid catalyzed conditions and in the presence of a mixture of an adamantane derivative and a surfactant as a combination surfactant/hydride transfer catalyst.
2. Brief Description of the Prior Art
The alkylation of olefins with isobutane, which proceeds by the addition of carbonium ions to the olefins under strong acid conditions, is a well-known process in the art for producing a wide variety of useful hydrocarbon materials and particularly, gasoline blending components. For example, 2,2,4-trimethylpentane is a common blending component which is used for octane improvement of motor gasoline and can be produced by alkylating butenes with isobutane in sulfuric acid or liquid HF. An example of such an acid catalyzed reaction process is described in U.S. Pat. No. 3,231,633.
Further examples of acid-catalyzed hydrocarbon conversion processes employing novel Lewis acid systems are disclosed in U.S. Pat. No. 4,229,611 and U.S. Pat. No. 4,162,233, both assigned to Exxon Research and Engineering Company.
In a related case, U.S. Pat. No. 3,671,598 describes a process for isomerizing saturated cyclic hydrocarbons under strong acid conditions in the presence of an adamantane hydrocarbon.
Further, U.S. Pat. Nos. 4,357,481; 4,357,484; 4,357,482; and 4,357,483 to George M. Kramer (issued Nov. 2, 1982, and assigned to Exxon Research and Engineering Company) disclose the use of adamantane hydrocarbons in paraffin-olefin alkylation and non-cyclic paraffin isomerization, and the use of aminoalkyladamantanes in paraffin-olefin alkylation and non-cyclic paraffin isomerization, respectively, in which rates of reaction are substantially increased as compared to those obtained in the absence of the specifically disclosed adamantane.
There is a constant search in the art for discovering processes for producing alkylated paraffinic hydrocarbons such as C.sub.8 branched hydrocarbons, which are currently used as octane improvement agents. These desired processes should preferably increase product quality and process economy and efficiency, factors which are reflected in terms of fewer side reactions, less acid catalyst consumption and faster desirable reaction rates. Overall, these process parameters result in improved product quality in terms of motor octane number and yield. Specifically, what is desired is a process which inhibits the side reaction of "cracking", which involves the catalytic degradation of the desired product, C.sub.8 branched hydrocarbons, to other hydrocarbons which are not as useful for octane improvement.